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Shock-wave-induced fracturing of calcareous nannofossils from the Chesapeake Bay impact crater

Geology

By:
DOI: 10.1130/G19678.1

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Abstract

Fractured calcareous nannofossils of the genus Discoaster from synimpact sediments within the Chesapeake Bay impact crater demonstrate that other petrographic shock indicators exist for the cratering process in addition to quartz minerals. Evidence for shock-induced taphonomy includes marginal fracturing of rosette-shaped Discoaster species into pentagonal shapes and pressure- and temperature-induced dissolution of ray tips and edges of discoasters. Rotational deformation of individual crystallites may be the mechanism that produces the fracture pattern. Shock-wave-fractured calcareous nannofossils were recovered from synimpact matrix material representing tsunami or resurge sedimentation that followed impact. Samples taken from cohesive clasts within the crater rubble show no evidence of shock-induced fracturing. The data presented here support growing evidence that microfossils can be used to determine the intensity and timing of wet-impact cratering.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Shock-wave-induced fracturing of calcareous nannofossils from the Chesapeake Bay impact crater
Series title:
Geology
DOI:
10.1130/G19678.1
Volume
31
Issue:
8
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geology
First page:
697
Last page:
700